Metabolic and morphological alterations induced by proteolysis-inducing factor from Walker tumour-bearing rats in C2C12 myotubes

Conditioned Media from Head and Neck Cancer Cell Lines and Serum Samples from Head and Neck Cancer Patients Drive Catabolic Pathways in Cultured Muscle Cells

BACKGROUND

The role of secreted factors from the tumor cells in driving cancer cachexia and especially muscle loss is unknown. We wanted to study both the action of secreted factors from head and neck cancer (HNC) cell lines and circulating factors in HNC patients on skeletal muscle protein catabolism.

METHODS

Conditioned media (CM) made from head and neck cancer cell lines and mix of sera from head and neck cancer (HNC) patients were incubated for 48 h with human myotubes. The atrophy and the catabolic pathway were monitored in myotubes. The patients were classified regarding their skeletal muscle loss observed at the outset of management.

RESULTS

Tumor CM (TCM) was able to produce atrophy on myotubes as compared with control CM (CCM). However, a mix of sera from HNC patients was not able to produce atrophy in myotubes. Despite this discrepancy on atrophy, we observed a similar regulation of the catabolic pathways by the tumor-conditioned media and mix of sera from cancer patients. The catabolic response after incubation with the mix of sera seemed to depend on the muscle loss seen in patients.

CONCLUSION

This study found evidence that the atrophy observed in HNC patients cannot be solely explained by a deficit in food intake.

Leucine-Rich Diet Modulates the Metabolomic and Proteomic Profile of Skeletal Muscle during Cancer Cachexia

Background: Cancer-cachexia induces a variety of metabolic disorders, including skeletal muscle imbalance. Alternative therapy, as nutritional supplementation with leucine, shows a modulatory effect over tumour damage in vivo and in vitro. Method: Adult rats distributed into Control (C), Walker tumour-bearing (W), control fed a leucine-rich diet (L), and tumour-bearing fed a leucine-rich diet (WL) groups had the gastrocnemius muscle metabolomic and proteomic assays performed in parallel to in vitro assays. Results: W group presented an affected muscle metabolomic and proteomic profile mainly related to energy generation and carbohydrates catabolic processes, but leucine-supplemented group (WL) recovered the energy production. In vitro assay showed that cell proliferation, mitochondria number and oxygen consumption were higher under leucine effect than the tumour influence. Muscle proteomics results showed that the main affected cell component was mitochondria, leading to an impacted energy generation, including impairment in proteins of the tricarboxylic cycle and carbohydrates catabolic processes, which were modulated and improved by leucine treatment. Conclusion: In summary, we showed a beneficial effect of leucine upon mitochondria, providing information about the muscle glycolytic pathways used by this amino acid, where it can be associated with the preservation of morphometric parameters and consequent protection against the effects of cachexia.

Promising models for cancer-induced cachexia drug discovery

Introduction: Cachexia is a frequent, multifactorial syndrome associated with cancer afflicting patients' quality of life, their ability to tolerate anti-neoplastic therapies and the therapies efficacy, as well as survival. Currently, there are no approved cancer cachexia treatments other than those for the treatment of the underlying cancer. Cancer cachexia (CC) is poorly understood and hence makes clinical trial design difficult at best. This underlines the importance of well-characterized animal models to further elucidate the pathophysiology of CC and drug discovery/development.Areas covered: This review gives an overview of the available animal models and their value and limitations in translational studies.Expert opinion: Using more than one CC model to test research questions or novel compounds/treatment strategies is strongly advisable. The main reason is that models have unique signaling modalities driving cachexia that may only relate to subgroups of cancer patients. Human xenograph CC models require the use of mice with a compromised immune system, limiting their value for translational experiments. It may prove beneficial to include standard care chemotherapy in the experimental design, as many chemotherapeutic agents can induce cachexia themselves and alter the metabolic and signaling derangements of CC and thus the response to new therapeutic strategies.

Effects of conditioned media from murine lung cancer cells and human tumor cells on cultured myotubes

Factors secreted from tumors/tumor cells are hypothesized to cause skeletal muscle wasting in cancer patients. We examined whether cancer cells secrete factors to promote atrophy by evaluating the effects of conditioned media (CM) from murine lung cancer cells and primary cultures of human lung tumor cells on cultured myotubes. We evaluated murine Lewis lung carcinoma (LLC) and KRAS^G12D cells, and primary cell lines derived from tumor biopsies from patients with lung cancer (hTCM; n = 6). In all experiments, serum content was matched across treatment groups. We hypothesized that CM from murine and human tumor cells would reduce myotube myosin content, decrease mitochondrial content, and increase mitochondrial reactive oxygen species (ROS) production. Treatment of myotubes differentiated for 7 days with CM from LLC and KRAS^G12D cells did not alter any of these variables. Effects of murine tumor cell CM were observed when myotubes differentiated for 4 days were treated with tumor cell CM and compared with undiluted differentiation media. However, these effects were not apparent if tumor cell CM treatments were compared with control cell CM or dilution controls. Finally, CM from human lung tumor primary cell lines did not modify myosin content or mitochondrial content or ROS production compared with either undiluted differentiated media, control cell CM, or dilution controls. Our results do not support the hypothesis that factors released from cultured lung cancer/tumor cells promote myotube wasting or mitochondrial abnormalities, but we cannot dismiss the possibility that these cells could secrete such factors in vivo within the native tumor microenvironment.

A leucine-rich diet modulates the mTOR cell signalling pathway in the gastrocnemius muscle under different Walker-256 tumour growth conditions

Background

The exact signalling mechanism of the mTOR complex remains a subject of constant debate, even with some evidence that amino acids participate in the same pathway as used for insulin signalling during protein synthesis. Therefore, this work conducted further study of the actions of amino acids, especially leucine, in vivo, in an experimental model of cachexia. We analysed the effects of a leucine-rich diet on the signalling pathway of protein synthesis in muscle during a tumour growth time-course.

Methods

Wistar rats were distributed into groups based on Walker-256 tumour implant and subjected to a leucine-rich diet and euthanised at three different time points following tumour development (the 7th, 14th and 21st day). We assessed the mTOR pathway key-proteins in gastrocnemius muscle, such as RAG-A-GTPase, ERK/MAP4K3, PKB/Akt, mTOR, p70S6K1, Jnk, IRS-1, STAT3, and STAT6 comparing among the experimental groups. Serum WF (proteolysis-induced factor like from Walker-256 tumour) and muscle protein synthesis and degradation were assessed.

Results

The tumour-bearing group had increased serum WF content, and the skeletal-muscle showed a reduction in IRS-1 and RAG activation, increased PKB/Akt and Erk/MAP4K3 on the 21st day, and maintenance of p70S6K1, associated with increases in muscle STAT-3 and STAT-6 levels in these tumour-bearing rats.

Conclusion

Meanwhile, the leucine-rich diet modulated key steps of the mTOR pathway by triggering the increased activation of RAG and mTOR and maintaining JNK, STAT-3 and STAT-6 levels in muscle, leading to an increased muscle protein synthesis, reducing the degradation during tumour evolution in a host, minimising the cancer-induced damages in the cachectic state.

Invasion of TC-1 cells to skeletal muscle fibers protect them from peroxisomicine A1 (T-514) treatment in a murine model of cancer

T-514 or Peroxisomicine A1 (PA1) is a toxin isolated from plants of genus Karwinskia. In vitro studies described selective toxicity of PA1 on malignant cell lines. A toxic effect of PA1 on TC-1 cells in vivo was reported. The objective was to evaluate the effect of PA1 over invasion of TC-1 cells to muscle fibers in vivo. TC-1 cells were implanted in 36 mice divided in two groups (n: 18): treated with PA1 or with vehicle, a control group was included. At 10 days, nine mice of each group were euthanized. TC-1 implant site was analyzed by light and electron microscopy, a morphometric study was also performed. Remaining mice were used to evaluate tumor growth and survival time. Results show tumor cells between muscle fibers, with diminution in diameter, change in the staining pattern, loss of continuity of external lamina, and sarcoplasm with tumor cells. Statistically difference was observed between treated group vs control group. PA1 decreased tumor growth and increased the survival time in treated mice. The degree of resistant activity, aggressiveness, and invasiveness of TC-1 cells described in present work; should be taken into account in studies that evaluate effectiveness of therapies using this cancer model.

Metformin treatment modulates the tumour-induced wasting effects in muscle protein metabolism minimising the cachexia in tumour-bearing rats

Background

Cancer-cachexia state frequently induces both fat and protein wasting, leading to death. In this way, the knowledge of the mechanism of drugs and their side effects can be a new feature to treat and to have success, contributing to a better life quality for these patients. Metformin is an oral drug used in type 2 diabetes mellitus, showing inhibitory effect on proliferation in some neoplastic cells. For this reason, we evaluated its modulatory effect on Walker-256 tumour evolution and also on protein metabolism in gastrocnemius muscle and body composition.

Methods

Wistar rats received or not tumour implant and metformin treatment and were distributed into four groups, as followed: control (C), Walker 256 tumour-bearing (W), metformin-treated (M) and tumour-bearing treated with metformin (WM). Animals were weighed three times a week, and after cachexia state has been detected, the rats were euthanised and muscle and tumour excised and analysed by biochemical and molecular assays.

Results

Tumour growth promoted some deleterious effects on chemical body composition, increasing water and decreasing fat percentage, and reducing lean body mass. In muscle tissue, tumour led to a decreased protein synthesis and an increased proteolysis, showing the higher activity of the ubiquitin-proteasome pathway. On the other hand, the metformin treatment likely minimised the tumour-induced wasting state; in this way, this treatment ameliorated chemical body composition, reduced the higher activities of proteolytic enzymes and decreased the protein waste.

Conclusion

Metformin treatment not only decreases the tumour growth but also improves the protein metabolism in gastrocnemius muscle in tumour-bearing rats.

Dietary leucine supplementation minimises tumour-induced damage in placental tissues of pregnant, tumour-bearing rats

Background

The occurrence of cancer during pregnancy merges two complex, poorly understood metabolic and hormonal conditions. This association can exacerbate the conditions of both the mother and the foetus. The branched-chain amino acid leucine enhances cellular activity, particularly by increasing protein synthesis. This study aimed to analyse the modulatory effect of a leucine-rich diet on direct and indirect tumour-induced placental damage. This was accomplished by evaluating the expression of genes involved in protein synthesis and degradation and assessing anti-oxidant enzyme activity in placental tissues collected from pregnant, tumour-bearing rats.

Results

Pregnant rats were either implanted with Walker 256 tumour cells or injected with ascitic fluid (to study the indirect effects of tumour growth) and then fed a leucine-rich diet. Animals in a control group underwent the same procedures but were fed a normal diet. On the 20^th day of pregnancy, tumour growth was observed. Dams fed a normoprotein diet showed the greatest tumour growth. Injection with ascitic fluid mimicked the effects of tumour growth. Decreased placental protein synthesis and increased protein degradation were observed in both the tumour-bearing and the ascitic fluid-injected groups that were fed a normoprotein diet. These effects resulted in low placental DNA and protein content and high lipid peroxidation (measured by malondialdehyde content). Decreased placental protein synthesis-related gene expression was observed in the tumour group concomitant with increased expression of genes encoding protein degradation-associated proteins and proteolytic subunits.

Conclusions

Consumption of a leucine-rich diet counteracted the effects produced by tumour growth and injection with ascitic fluid. The diet enhanced cell signalling, ameliorated deficiencies in DNA and protein content, and balanced protein synthesis and degradation processes in the placenta. The improvements in cell signalling included changes in the mTOR/eIF pathway. In conclusion, consumption of a leucine-rich diet improved placental metabolism and cell signalling in tumour-bearing rats, and these changes reduced the deleterious effects caused by tumour growth.

Proteomic analysis of media from lung cancer cells reveals role of 14-3-3 proteins in cachexia

Aims: At the time of diagnosis, 60% of lung cancer patients present with cachexia, a severe wasting syndrome that increases morbidity and mortality. Tumors secrete multiple factors that contribute to cachectic muscle wasting, and not all of these factors have been identified. We used Orbitrap electrospray ionization mass spectrometry to identify novel cachexia-inducing candidates in media conditioned with Lewis lung carcinoma cells (LCM). Results: One-hundred and 58 proteins were confirmed in three biological replicates. Thirty-three were identified as secreted proteins, including 14-3-3 proteins, which are highly conserved adaptor proteins known to have over 200 binding partners. We confirmed the presence of extracellular 14-3-3 proteins in LCM via western blot and discovered that LCM contained less 14-3-3 content than media conditioned with C2C12 myotubes. Using a neutralizing antibody, we depleted extracellular 14-3-3 proteins in myotube culture medium, which resulted in diminished myosin content. We identified the proposed receptor for 14-3-3 proteins, CD13, in differentiated C2C12 myotubes and found that inhibiting CD13 via Bestatin also resulted in diminished myosin content. Conclusions: Our novel findings show that extracellular 14-3-3 proteins may act as previously unidentified myokines and may signal via CD13 to help maintain muscle mass.

Analysis of Y-P30/Dermcidin expression and properties of the Y-P30 peptide

BACKGROUND

The survival promoting peptide Y-P30 has a variety of neuritogenic and neuroprotective effects in vitro and in vivo. In previous work we reported the expression of Y-P30/dermcidin in maternal peripheral blood mononuclear cells (PBMCs) and the transport of the protein to the fetal brain. In this study we analyzed hormonal regulation of Y-P30 in human immune cells and expression of Y-P30 in the placenta. We further studied the stability and secretion of the Y-P30 peptide.

RESULTS

We found indications that Y-P30 might be produced in human placenta. The Y-P30 mRNA was rarely found in isolated human PBMCs and alpha-feto-protein, human chorionic gonadotropin as well as estradiol combined with progesterone could not induce Y-P30 expression. Y-P30 was found to be extraordinarily stable; therefore, contamination with the peptide and the Y-P30/Dermcidin precursor mRNA is a serious concern in experiments looking at the expression of Y-P30/Dermcidin. In cultured cell lines and primary neurons we found that Y-P30 could be released, but neuronal uptake of Y-P30 was not observed.

CONCLUSIONS

Our data suggest that a source of Y-P30 apart from eccrine glands might be the placenta. The peptide can be secreted together with the signaling peptide and it might reach the fetal brain where it can exert its neuritogenic functions by binding to neuronal membranes.

Binding of Y-P30 to syndecan 2/3 regulates the nuclear localization of CASK

The survival promoting peptide Y-P30 has documented neuroprotective effects as well as cell survival and neurite outgrowth promoting activity in vitro and in vivo. Previous work has shown that multimerization of the peptide with pleiotrophin (PTN) and subsequent binding to syndecan (SDC) -2 and -3 is involved in its neuritogenic effects. In this study we show that Y-P30 application regulates the nuclear localization of the SDC binding partner Calcium/calmodulin-dependent serine kinase (CASK) in neuronal primary cultures during development. In early development at day in vitro (DIV) 8 when mainly SDC-3 is expressed supplementation of the culture medium with Y-P30 reduces nuclear CASK levels whereas it has the opposite effect at DIV 18 when SDC-2 is the dominant isoform. In the nucleus CASK regulates gene expression via its association with the T-box transcription factor T-brain-1 (Tbr-1) and we indeed found that gene expression of downstream targets of this complex, like the GluN2B NMDA-receptor, exhibits a corresponding down- or up-regulation at the mRNA level. The differential effect of Y-P30 on the nuclear localization of CASK correlates with its ability to induce shedding of the ectodomain of SDC-2 but not -3. shRNA knockdown of SDC-2 at DIV 18 and SDC-3 at DIV 8 completely abolished the effect of Y-P30 supplementation on nuclear CASK levels. During early development a protein knockdown of SDC-3 also attenuated the effect of Y-P30 on axon outgrowth. Taken together these data suggest that Y-P30 can control the nuclear localization of CASK in a SDC-dependent manner.

Leucine-rich diet supplementation modulates foetal muscle protein metabolism impaired by Walker-256 tumour

BACKGROUND

Cancer-cachexia induces a variety of metabolic disorders of protein turnover and is more pronounced when associated with pregnancy. Tumour-bearing pregnant rats have impaired protein balance, which decreases protein synthesis and increases muscle breakdown. Because branched-chain amino acids, especially leucine, stimulate protein synthesis, we investigated the effect of a leucine-rich diet on protein metabolism in the foetal gastrocnemius muscles of tumour-bearing pregnant rats.

METHODS

Foetuses of pregnant rats with or without Walker 256 tumours were divided into six groups. During the 20 days of the experiment, the pregnant groups were fed with either a control diet (C, control rats; W, tumour-bearing rats; Cp, rats pair-fed the same normoprotein-diet as the W group) or with a leucine-rich diet (L, leucine rats; LW, leucine tumour-bearing rats; and Lp, rats pair-fed the same leucine-rich diet as the LW group). After the mothers were sacrificed, the foetal gastrocnemius muscle samples were resected, and the protein synthesis and degradation and tissue chymotrypsin-like, cathepsin and calpain enzyme activities were assayed. The muscle oxidative enzymes (catalase, glutathione-S-transferase and superoxide dismutase), alkaline phosphatase enzyme activities and lipid peroxidation (malondialdehyde) were also measured.

RESULTS

Tumour growth led to a reduction in foetal weight associated with decreased serum protein, albumin and glucose levels and low haematocrit in the foetuses of the W group, whereas in the LW foetuses, these changes were less pronounced. Muscle protein synthesis (measured by L-[3H]-phenylalanine incorporation) was reduced in the W foetuses but was restored in the LW group. Protein breakdown (as assessed by tyrosine release) was enhanced in the L and W groups, but chymotrypsin-like activity increased only in group W and tended toward an increase in the LW foetuses. The activity of cathepsin H was significantly higher in the W group foetuses, but the proteolytic calcium-dependent pathway showed similar enzyme activity. In parallel, an intense oxidative stress process was observed only in the group W foetuses.

CONCLUSIONS

These data suggested that the proteasomal and lysosomal proteolytic pathways and oxidative stress are likely to participate in the process of foetal muscle catabolism of Walker's tumour-bearing pregnant rats. The present work shows that foetal muscle can be protected by supplementation with a leucine-rich diet.

Muscle wasting in animal models of severe illness

Muscle wasting is a serious complication of various clinical conditions that significantly worsens the prognosis of the illnesses. Clinically relevant models of muscle wasting are essential for understanding its pathogenesis and for selective preclinical testing of potential therapeutic agents. The data presented here indicate that muscle wasting has been well characterized in rat models of sepsis (endotoxaemia, and caecal ligation and puncture), in rat models of chronic renal failure (partial nephrectomy), in animal models of intensive care unit patients (corticosteroid treatment combined with peripheral denervation or with administration of neuromuscular blocking drugs) and in murine and rat models of cancer (tumour cell transplantation). There is a need to explore genetically engineered mouse models of cancer. The degree of protein degradation in skeletal muscle is not well characterized in animal models of liver cirrhosis, chronic heart failure and chronic obstructive pulmonary disease. The major difficulties with all models are standardization and high variation in disease progression and a lack of reflection of clinical reality in some of the models. The translation of the information obtained by using these models to clinical practice may be problematic.

Ultrastructural and stereological analysis of walker 256 carcinosarcoma cells at various stages of their differentiation

Ultrastructural and stereological study of Walker 256 carcinosarcoma cells implanted into the femoral muscle of Wistar rats was performed. Two types of Walker 256 carcinosarcoma cells were distinguished and their ultrastructural analysis was carried out. Five differentiation stages were described for each of the two cell types. Differentiation of carcinosarcoma cells was associated with a decrease of the nucleus/cytoplasm ratio, enlargement of the cell, and hyperplasia of granular cytoplasmic reticulum elements, fixed ribosomes, and mitochondria. Differences in the ultrastructure of the two cell types at similar differentiation stages were detected.